Various specifications, such as IEC 60947-1 and DIN EN 60204-1, require electrical switching devices in specific installation situations to be capable, in the OFF position of the switching device, of being safeguarded against being switched on again by means of one or more padlocks in order for example to prevent an electrical installation from being switched on again while maintenance work is being carried out on the installation. There are requirements that the OFF position be safeguarded by means of up to 4 padlocks.
CH 631 828 A5 describes an interlockable lock-out handle system. A base plate, which is mountable onto an operating shaft of a rotary switch and is fastenable to the rotary switch or a device front plate from the front, contains a lock-out disk that is mountable in rotational engagement onto the operating shaft and has at least one recess, a strip-shaped locking bar that is displaceable laterally for engagement in the recess of the lock-out disk, and a slide that is moulded vertically onto the locking bar and extends parallel to the bottom edge of the base plate. The slide at one end projects laterally from the base plate and is acted on at the other end by a compression spring. A cover that is mountable onto the base plate covers the base plate and the slide. The slide and the part of the cover that surrounds the slide are provided with holes, which correspond in the pressed state of the slide and into which at least one padlock or bracket lock is insertable for interlocking the rotary switch. In this interlocked state the cover cannot be removed, so that a release of the interlock is not possible. The drawbacks are the overall size, which is unsatisfactory due to the closing apparatus being separate from the rotary handle, and the number of components.
DE 42 06 378 A1 describes an interlockable lock-out handle system which forms, with an operating shaft of a switching device, a positive connection in the direction of rotation and is snap-mounted in the axial direction positively or non-positively on the operating shaft, and which comprises as a closing apparatus a swivel lever, which in the swivelled position blocks both the rotational movement of the rotary handle and the removal from the operating shaft. Closing- or lead-sealing apparatuses may be inserted into bores of the swivel lever as protection against unauthorised operation. The drawback of this solution is that the operating shaft end has to be matched very precisely to the lug of the swivel lever, this being impossible to carry out in the case of differing clearances of the switch from the front plate or in the case of differing front plate thicknesses.
DE-AS 12 00 923 describes a closable actuating apparatus comprising a rotary handle that is fastened by means of a locking pin on the operating shaft of a rotary switch. Pivotably mounted in the rotary handle is a lock-out lever in a bearing block, which is held in a cut-out of the rotary handle and in which there is mounted in an axially movable manner a lock-out pin, which is coupled non-positively to the lock-out lever and engages in a corresponding cut-out of the rotary switch housing. The lock-out lever is movable in an open groove, facing away from the rotary switch of the rotary handle, and is provided with an oblong hole for receiving padlocks. In the rest position the lock-out lever has a working surface that projects slightly from the lateral surface of the rotary handle. A helical spring that is supported on the one hand against a base plate of the bearing block and on the other hand against a dog of the lock-out bolt holds the lock-out lever in the rest position thereof. A transverse pin connects the lock-out bolt via an oblong hole to the lock-out lever. The drawbacks are that fastening the rotary handle on the operating shaft is a laborious process requiring precise measurement and that there is no possibility of carrying out modifications with regard to the closing positions.
DE 43 21 981 C2 describes a closable actuating device for a rotary switch comprising a cover, which is latched onto the front of the rotary switch and through which the operating shaft of the rotary switch extends, comprising a rotary handle, which is fastened in rotational engagement on the operating shaft and seated in front of the cover and has a closing aperture for a padlock that is to be fitted, and comprising an externally actuable lock-out slide that is mounted so as to be displaceable at right angles to the operating shaft axis in the rotary handle in order to block and/or clear the closing aperture. The cover is held together with the rotary handle and the lock-out slide by means of a retaining ring to form an assembly group that is mountable onto the rotary switch. The lock-out slide, which is provided with an actuating extension, is substantially rectangular and has on its side facing the rotary switch a groove, which in the lock-out position of the rotary handle moves out of coincidence with a guide collar of the cover, instead of which however a shoulder situated alongside the groove positions itself in a blocking manner against a gap of the guide collar. The drawback of this solution is that it is always fixed with regard to the positions of its closable operating position and does not allow any additional closing positions.
Finally, DE 196 03 238 C1 describes a closable actuating apparatus for a rotary table in which a lock-out slide serving as a closing apparatus is used to actuate a lock-out bolt, which in turn comes into lock-out operation with a rotationally engaged lock-out disk. The rotary handle that is tightly non-positively clamped on the operating shaft is incorporated into the lock-out bolt. By selecting the number and the angular position of the cut-outs in the lock-out disk that are provided for the lock-out bolt, the number and angular position of the closable operating positions of the rotary switch may be defined. In the handle part of the rotary handle a closing through-opening is provided for fitting padlocks. The drawback of this solution is that, because there is only limited space available in the handle part, only fewer than 4 padlocks may be fitted.
The company Eaton Industries, in its catalogue HPL 2010, offers a rotary handle with lock-out rim SVB, wherein the rotary handle may be safeguarded via the lock-out rim against unauthorised switching-on by means of up to three padlocks. In order to meet the requirement for a fourth lock, a fourth hole in the rotary handle and rim is conceivable but then there would also be a closing facility in positions that are not permitted in the standards. For example, in the case of contacts welded in the ON position in the basic unit, the handle could be rotated far enough in the OFF direction to enable a lock to be fitted and give the impression of a safe OFF position.